This invention relates to the field of treatment of water contained in enclosures. Such enclosures are typically swimming pools, spas, whirlpool tubs and cooling towers.
Boron and halogen-containing compounds, specifically chlorine-containing compounds, are often added to water contained in enclosures such as swimming pools, spas, whirlpool tubs, and cooling towers to inhibit bacteria, algae and fungal growth. However, in order to be effective against microorganisms such as bacteria, algae and fungus, it is necessary to maintain a particular concentration of halogen in the water. Using chlorine in swimming pools, for example, it is desirable to maintain an available chlorine content of about 0.4 to about 1.5 parts per million (ppm). Although boron and halogen-containing compounds, such as chlorine-containing compounds, are excellent water treatment agents, there are several inherent problems. For example, chlorine which has been directly added to a pool as elemental chlorine or as a hypochlorite, will gradually degrade. This loss of chlorine is accelerated in direct sunlight. Thus, it is necessary to continuously replace the lost chlorine. Another disadvantage of treating water in enclosures by direct addition of chlorine to the water is that the chlorine reacts with the water to form hydrochloric acid. The formation of hydrochloric acid causes a drop in the pH of the water and makes acid-base balancing difficult. Thus, when using chlorine as a water treatment agent, it is also necessary to add a buffer system to the water in order to maintain a proper pH level.
Another method of controlling water-borne microorganisms is through the use of halogen-substituted organics such as trichloro-S-triazinetrione, bromochlorodimethylhydantoin and trichloroisocyanuric acid (TCCA). This class of water treatment agents do not dissipate as rapidly as other chlorine and boron-containing compounds and are much easier to handle and to store. However, they can be quite expensive and a buffering system is still required to maintain a proper pH level.
Yet another method of treating water involves the use of chlorine generators in salt-water enclosures, such as pools or spas. Chlorine generators use electrolysis to produce chlorine/hypochlorous acid directly into the pool or spa from a low concentration of salt added to the water. Electrolysis takes place in an electrolytic cell installed inline in the recirculation system. Inside the cell are layers of metal plates electrically charged by a separate power supply. Preferably, a salt concentration of about 2500 ppm to about 6000 ppm in the water contained in the enclosure is maintained for the chlorine generator to operate effectively.
Chlorine generators create a better, healthier swimming or bathing experience for most people. It is not necessary to handle or buy chlorine or chlorine-containing compounds, and if the unit is functioning correctly, sufficient chlorine will be present in the enclosure to inhibit bacteria, algae and fungal growth. Unfortunately, the chlorine generators tend to become inefficient too quickly, due to corrosion of their special electrolyte plates.